Any opinions / reviews on Gemtune APPJ PA1502A

Discussion in 'Headphone Amps (full-size)' started by mortus, Sep 6, 2015.
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  1. braaam
    Nah, just a bot to keep some level of activity around here :wink:

    The Mazda’s are sometimes hard to identify. Interesting enough, Mazda never really manufactored its own tubes, but instead rebranded them.

    Mazda France started in the early 50s and Mazda was used as a brandname in the UK a lot later. They were only losely related through Thomson, the parent company. The Mazda tubes from the UK, which mostly originate from the late 60’, are often rebadged Brimars, and sound close to the Mullards and Philips tubes of that time!

    Going from your description, I suspect yours may be relabelled Brimars. Do you have a picture of them? The UK Mazda’s mosty come in blue packaging and labeling. The Mazda tubes from France, which came earlier, have different characteristics and often carry a white or golden label.

    If you look at the French silver plate versions, and compare them to the early GE 5751 design, you will see that they are almost identical. In the 50s, GE owned part of Mazda France. They also owned the Mazda trademark which was used for premium quality incandescant bulbs in the 30s.

    To me, the silver plate Mazda sounds more open than Mullards, with a more even balance and better extension at the top and less emphasis on the mids. They have their own unique sound signature, but if you like the GE’s you may want to give it a go if you can get a hold of one! They do share the openness and transparancy with the early 50s/60s GE tubes.
  2. baronbeehive
    Ha ha, from one bot to another programmed to keep this thread alive....

    thanks for the info, that's cleared up one or two things. I didn't really go into it but I was wondering what I got, a Mullard with Mazda brand or Mazda made in England, whatever, anyway I'm not too concerned, either way I wanted to try the Mullard/Mazda type sound. I thought it might be a Mullard but what you say is interesting, I have heard a Brimar in my 6SN7 amp and the sound is remarkably similar despite this one being a 12AX7, very dynamic, vivid sound. I said that I didn't know what to think and that was because I didn't really like the Brimar/Mullard type sound first time round, or at least it was too overpowering for easy listening, nevertheless it is amazing. I think it might be good on the headphone amp, mine is the speaker amp.

    I think I would prefer the silver plate Mazda. I didn't know about that until recently. I hadn't noticed the likeness to the GE's but you're right, it does resemble them, except for the silver colour plates, also the slots.

    I have tried the 12SL7 GE's on my speaker amp and these are a bit unusual in that they have round sections in the middle of the plates where it is normally box construction, and silver plates so I don't know how representative they are of GE's in general. That's why I was interested in trying another type such as the 14F7 which I have on order, or a cryo GE 5751 from watford Valves. I really love the transparency but was put off by the slightly thin, slightly harsh sound but it's not that pronounced and works really well in my amp.
    Last edited: Dec 31, 2017
  3. baronbeehive
    These are a couple of pics, not brilliant but you get the idea:

    The tube has a code: 40D near the bottom, which I could not decipher, has got the Mullard designation: BVA, without the shield, depite saying Made In Holland, and has the 4 seams on the top of the glass that Amperex's have got and appears to be made for export. My feeling is that it is a late 1950's - early 1960's Mullard with Mazda brand or Mazda made by Mullard. It sounds Mullard like, and quite like Brimar also, but is quite aggressive and tubey sounding which is why my guess is Mullard. Bit complicated: A french Mazda, with British made code, and made in Holland label, and difficult to tell from looking at them!! At least the silver anode is fairly straightforward! What do you think?


    Last edited: Dec 31, 2017
  4. braaam
    These are great tubes! The first etched character is most likely not a 4, but a triangle, which is the factory code for Philips Heerlen. The 2nd character, the zero, stands for the year. This type with the shorter plates was made from around 1959 untill end 70s. The earlier ones did have the 4 seems on top, and a bigger halo getter. Yours then looks to be from 1960, a very good vintage!

    BVA was used by multiple British tube manufactorers - Brimar as well - it was a stamp for good quality products.

    The Philips tubes in general are more lively then Mullards, have a bit less mid emphasis but are still very smooth in sound. A favourite of many - personally I prefer them to most Mullards. The earlier long plate variants can sound even better, but yours should be close to these in sound.
    Maxx134 likes this.
  5. baronbeehive
    Thanks braaam for that valuable information! I had difficulty with those codes, they kept changing them. I'm glad I finally tried these tubes, but am really thinking that I would like to check out those silver anode Mazdas, as that is more my type of sound...... but I will keep the Mullards/Philips for curiousity value!

    Edit: Quick update. I'm loving this tube, I'm completely won over, the 3d soundstage and the detail in the midrange, voices, for example, are wonderful.

    Edit2: Just tried the 14AF7 GE's and they're pretty crap, especially after the Mullard's. Thin, flat, and boring sounding, I don't think I will be spending any more time with them. The plates are different to the 12SL7 GE's which I like, they seem to be much more musical sounding than the 14AF7's.

    That's the end of my tube rolling, hope that's been of interest, it's been fun seeing how different this amp can sound!

    I don't like keeping lots of superfluous tubes lying around as I've settled on my favourites and it's not worth putting them on ebay so if anyone is having any difficulty getting anything they could PM me you can have them for a nominal sum, they're all good and pretty cheap. I have a few different types: Amperex 12AX7, Philips Miniwatt 12AX7, TJ Full Music 12AX7 (new issue), Tungsol 12AX7 (new issue), GE 14AF7, Tungsol 14AF7, RCA 14F7, GE 12SL7 and a matched pair of nos Russian 6F6C Kobra's. I just want to de-clutter!
    Last edited: Jan 23, 2018
  6. Maxx134
    I agree totally.
    I have an old Millard 12au7 that has a bit too much euphoric mids and is supposed to be more neutral than the 12ax7 type.
    I will have to compare them again.

    Looks like I have to try them haha
  7. Mshenay Contributor
    Yea I've not listened to this bad boi since October! Hooked everything back up today and I'm kinda impressed how well it does with my AKG K240 Sextett, though I am driving High gain out of my DAC and High Gain from the amp it self. Not sure if this is rated for a 600Ohm but it's doing pretty good. JJ 6V6s Power Tubes and a Sylvania 12SL7GT Jan CHS vt289

    The previous channel imbalances issues I had seem to be gone! In fact I'm really impressed with how well this handles stereo music, my K240 has a really nice cohesive sound stage! Quite impressive really. I've also reached out to a member here to have some Mods performed at a later date. I might just enjoy it stock for now since it seems to be working nicely! An check back in once said mods are complete'd.

    As for parts I'm kinda set on the

    ANKECAP-81784 Audio Note Kasie's that every one talks about 1000 uF an 25VDC

    For the Coupling Film Caps I like what I heard from David on the
    Auricap XO .47 400VDC

    My only question is about the Film Caps you guys have recommend installing in Parallel with the Electrolytic Cathodes, I saw the .047 recommendation. But I don't see film caps with the same 1000 uF 25VDC rating as the Electro's that they'd be in parallel with
    Last edited: Jan 19, 2018
  8. baronbeehive
    Higher voltage is not a problem, so I would go with the Auricap.047, or .1uF 400v for the cathode bypasses. They will then compliment the sound of your Auricap coupling caps and should sound great!

    I don't think they will fit though without extending the chassis which you could do by adding some aluminium heatsink sheets like Maxx and I did. But you mustn't shirk from bypassing your cathode caps, if you don't use bypasses the sound will suffer as a result as members here have found.
  9. baronbeehive
    Well, my final, final tube rolling experiment has finished with trying the silver anode Mazda, and.... I have nothing more to say, I have no more need of tube rolling, audio nirvana is at hand, with the 2 Mazdas I recently got, this one and the Philiips-Mazda branded tube!!!
    Last edited: Jan 20, 2018
    braaam likes this.
  10. Mshenay Contributor
    What would you recommend for upgrades without extending the Chassis?
  11. baronbeehive
    I've just had a look at the dimensions of the .47uF Auricaps which are 17x20mm, as against the Jupiters in my APPJ which are 21x52mm, and the .047uF Auricap bypasses would be 11x14mm, therefore it's possible you could locate your bypasses somewhere by the end of the Auricaps because 20+14=34mm which is still less than the length of my Jupiters. Otherwise you could try something like these:
    which are 7mm deep and may therefore fit over the Auricaps.

    The best thing would be to open up the bottom and measure yourself to see what would fit and then get that.
  12. Mshenay Contributor
    What about the
    What about the solen 0.1 ufs?
  13. baronbeehive
    I don't know about that but I definitely think you could do what I said with the Auricaps, it might need a bit of jiggery pokery but should work going by the dimensions, but it's up to you to check before you go ahead and order.
  14. Mshenay Contributor
    Good to know! At this point I'm trying to get the soldering done by some one else! I'm a little too busy right now and my soldering skills aren't quite up to par.

    I'm hoping to have this little guy modded and show ready by February!
  15. baronbeehive
    Do not delay.... this is worth it!!

    The pic shows that the length of the Jupiter caps should allow for your Auricap/bypass cap end to end and you could take out one of those posts to make more room.

    Mshenay likes this.
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